You should be adept at bhopping before you try this out

Power bunnyhopping is possible if your 'cl_sidespeed' is set between 610-620

Open the console with the '~' key and enter 'cl_sidespeed 610' or 'cl_sidespeed 620' and remember this will have to be entered every time you open the game (or you could set up an autoexec file to do it)

Always run can be kept on

The video below shows how to perform power bunnyhops, just ignore the information from 0:07 to 0:14 (Don't change your 'cl_forwardspeed' !!)